Re: [Xen-devel] [PATCH] xen/hvc: If we use xen_raw_printk let it also work on HVM guests.

[Ian Campbell <ian.campbell@xxxxxxxxxx>]

On Tue, 2013-08-20 at 15:35 -0400, Konrad Rzeszutek Wilk wrote:
>  void xen_raw_console_write(const char *str)
>  {
> -     dom0_write_console(0, str, strlen(str));
> +     ssize_t len = strlen(str);
> +     int rc = 0;
> +
> +     if (xen_domain()) {
> +             rc = dom0_write_console(0, str, len);
> +             if (rc != len && xen_hvm_domain()) /* -ENOSYS */

If you want to catch ENOSYS then I suggest doing so explicitly, rather
that relying on len != -ENOSYS.

> +                     goto outb_print;

How about reversing this into
        if (rc == len) return;
        if (rc != -ENOSYS) panic(...) /* yes, this won't get far... *.

Then fall through to the following block as a plain if not an else if.
Maybe with a xen_hvm_domain && added.

That avoids the yucky goto I think.

> +     } else if (xen_cpuid_base()) {
> +             int i;
> +outb_print:
> +             for (i = 0; i < len; i++)
> +                     outb(str[i], 0xe9);
> +     }
>  }
>  
>  void xen_raw_printk(const char *fmt, ...)



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